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well here goes, the 760 always ran flawlessly untill one day pulling away from a trafic light under full throttle the car just died out then kickd back in and off i went, since then it did it to me 2 other times about a week later. then yesterday i drove up my drivway (pretty steep) and just almost to the top and it died, would just crank no start and i smelled raw fuel out the tail pipe. about 4 hours later it started fine, so i parked it and it will not start now a day later. so i started checking for fuel, air, spark, well i got no spark. so i removed the coil and checked for power there, got + with the key on and also with it cranking but i get no (-) when cranking. does anybody know where the ignition modual or computer is located? i know its not on the pass side kick panel cause i had to replace the ecu when i went through a deep puddle once and somehow got water inside the car and in the computer, its still a mystery to me how the water got in the car. anyway does the crank sensor tell when to fire the ignition or is there a cam position sensor, i am a diesel mechanic and this is my first gas powered volvo, but before i goe tearing into things that might not be the cause maybe someone here can shed some light on the situation. thanks chris
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Have you resolved your problem yet? I had same problem on 1988 760 4 cyl. turbo. The probem turned out to be the Impulse Sensor (also known as Hall Switch or Hall Sensor) Replaced mine and problem was solved. The sensor is riveted in the aluminum distribitor with steel rivets. It is a real problem to drill out without damageing distribitor housing. A new distribitor has the switch in place, that is what I did. Good Luck!
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did some more testing. there are 3 wires to the crank sensor 1 is the shield/ground and the other 2 are signal, when i unplug it and crank over the injectors do not click, i get a voltage reading across the terminals of the sensor too so it seems to be working. plug it in and crank it over, injectors and fuel pump work, still no spark, take a trip to the local volvo junkyard(my friend deo) he gives me a coil and ignition modual off of his running car to try. put the modual in behind the air filter ......nada, put the coil in......nada. take my stuff to his house and put my coil and modual in his car vroooom. for haha's i decided to try changing the crank sensor, ......nope.
so does anybody know what i should test for at the plug for the modual, the blue wire i get 12v key on, what readings should i get from the other wires, and does anybody have a wiring diagram for the ignition circuit they can email me? thanks chris
ps: think im gonna go fix the old 760 gle turbodiesel, that never let me down till it started loosing compression 371,873 miles.
gotta do something, riding the motorcycle in the rain to work is gettin kinda old real fast.
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plug it in and crank it over, injectors and fuel pump work, still no spark,
I don't have much time on 700/900 cars and none with your '87 PRV. But that condition sounds like some early (?) version of EZK, with a bad final amplifier (aka "power stage") that does the Coil minus triggering.
We've had a rare 1 or 2 like that here — the only case I know of where the ignition is good up to and including the ICU, which then tells the Fuel ECU to go ahead. Thus giving you fuel but no spark.
Maybe some one with more late '80s 700 knowledge will ring in...
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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yup fuel injectors fire. it accually flooded the motor from trying to start so many times. so i unpluged the blue wire from the coil + side that goes to the FI ecu so the injectors are not clicking when its cranking, thus keeping it from flooding. i tried my friends portable ignition box just to see if everything with the FI side was good and it purred like a kitten. is there any other part of the ignition system that i missed, i checked and or replaced the folowing items, coil,the ignition box on drivers side inner fender behind air filter,FI relay,all fuses in the center consol,wiring and connectors were cleaned and sprayed with de-oxit. btw i wonder if the crank position sensor could give a good enough signal to kick the injectos but no spark?
chris
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I don't know of any wire (blue or other) that goes from coil to FI ecu.
The injectors stop because with the wire off coil +, there is no spark, so no "spark OK" signal/pulses to FI ecu.
I don't know anything about a "portable ignition box". Or how it could tell you "if everything with the FI side was good".
"the ignition box on drivers side inner fender behind air filter"
That sounds like the "power stage" that fires the coil -- or should.
"btw i wonder if the crank position sensor could give a good enough signal to kick the injectos but no spark?"
CPS doesn't signal the FI ecu in any way. It goes to the ignition system, which sends timing pulses to the FI ecu for injector grounding, etc.
Those pulses must be getting to the FI if you're getting fuel.
The problem is that the "final step" (coil pulsing) is failing.
But this is just guessing based on later systems that I know better.
Do you know which Ignition and FI systems you have?
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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the blue wire at the coil, if i feed 12v+ to it the fuel pump cycles on for a few seconds, if i crank over the engine the injectors pulse and pump runs, EVEN when the box behind the air filter is unpluged the injectors still pulse. but if i unplug the crank sensor the pump and injectors stay off while i crank. so this system must be different for the 2.8v6. do you know how to identify what systems i have?
i find that the prv v6 is not well documented and hard to find info on it. it has a check engine light but does NOT have the little box on the drivers strut tower with the probe and led light like every other volvo i owned(6 to date).
btw a portable ignition box connects to the battery and the spark plug wire from the coil gets connected to it, it makes a constant spark and alows the engine to run but only temporary as it can cause damage to cap, rotor and the timing is way out of wack using this box, but in a emergency it will get you somewhare a few miles to safety.
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Just guessing that you have some version of EZK Ignition, because you have a Crank Position Sender. My experience is on 240, not 700 or PRV, but EZK should be basically the same for all, except maybe for wire colors.
the blue wire at the coil, if i feed 12v+ to it the fuel pump cycles on for a few seconds,
• How/why are you "feeding +12v to the Coil? It's normal to get+12v on the blue wire (coil terminal #15?) with the key on. You might be somehow back-feeding a pulse to the EZK controller, which then lets the FI run for a few seconds. Could be semi-normal.
if i crank over the engine the injectors pulse and pump runs,
• That's because:
1 - the EZK is getting CPS pulses,
2 - "thinks" its generating spark OK,
3 - and signals the FI system to go.(should also be pulsing Power Stage to fire the coil at the same time)
(CPS pulses go only to the EZK, not to FI).
EVEN when the box behind the air filter is unpluged the injectors still pulse.
• That "box" sounds like the EZK Power Stage I keep suggesting. If so, it has nothing to do with injectors—but should be triggering the coil #1 terminal. Need to know more about it -- 5 wires? Including a R-W one and a Blue one? (Peel back the rubber boot on the plug to see wires.)
but if i unplug the crank sensor the pump and injectors stay off while i crank.
• Normal — No CPS signal to EZK means no EZK "Spark OK" signal to FI ECU.
so this system must be different for the 2.8v6. do you know how to identify what systems i have?
• Is your engine a B28 or B280? I think the B280 EZK "basics" are probably the same as I've been describing. Decal under the hood should tell which engine.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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its a b280. the number 15 terminal has 2 wires 1 that i traced back to the power stage and the other goes all the way to the FI ecu, this is the one i can put 12v+ to and cycle the pump. oh btw its a bosch coil But its on the drivers side strut tower, and every thing i am reading says bosch systems have it on the passenger side like my 89 740gle does.
the other terminal on the coil - has a white w/red stripe (trigger wire)
my power stage has 5 wires
white w/red
black
brown
blue
grey
chris
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its a b280. the number 15 terminal has 2 wires 1 that i traced back to the power stage and the other goes all the way to the FI ecu,...
That's where you're going off track. That's the EZK Ignition CU, not FI.
Ignition +12v comes to the coil #15 first, then goes to the EZK CU and the Power Stage on those 2 wires you traced.
With Key On, check wires at the Power Stage. Blue wire should have +12v, Brown wire should be ground. Other end of brown ground should be on the intake somewhere (along with another brown wire from the Ign. CU -- the one you thought was FI).
If voltage and ground are OK, the PS is probably shot. I think it runs hot, and depends on special heat-conducting mounting "grease" where it mounts to the inner fender. That stuff has probably dried out by now, and let the PS burn out or something. That's the usual problem posted here.
You'll want fresh grease if you replace the Power Stage. I think this is the right stuff.
Try a search on "Power Stage" here, or look in the 700/900 FAQ for possible tips.
As for parts locations -- they change over time and between models & engines. Just something we have to live with.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Chris, I was talking to Bruce about how little I know about EZ-K ignition before the EZ116K version used in the 200 series 89- cars. But since then I looked at some of the schemes here Russian 89 700 series wiring diagrams and noticed the power stages of all those use similar wiring color conventions:
Brown - ground
Blue - +12V with ignition on
Gray - from computerized spark controller (pulses to time ignition)
Red/white - to coil terminal 1
I'd agree with Bruce if your injectors receive the timing from the crank sensor's cue, your spark computer is processing it. The unknown now is just how the spark computer is getting it to the power stage and if it is, is that red/white wire you found good. Of course the power stage needs +12 and ground and it is in a lousy place for corroded wiring, right?
--
Art Benstein near Baltimore
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i agree about the lousy place for wiring behind the airbox. but i am luck that this car was NEVER driven in the snow and saw verry few rain drops either previous owner kept it mint, i wont drive it in the winter but i do in the rain, anyway the car looks like it rolled off the showroom floor, you can eat off the engine and i have yet to find any green on any wire or connection in the whole car :)
do you know how many volts aprox that i will see from the grey wire when cranking?
and i am going to go check the ground now too.
i wonder what the black wire is?
i will post what i find
thaks for the info
everybody on the brickboard has been so very helpfull in times of need, and i just like to say thanks for helping out and keeping another good 'ol volvo roaming around for my happy miles.
chris
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i will have to find my ezk computer because i get no square wave, (i have a fluk handheld multi meter scope) so either bad connection, a broken wire, or maybe water got somewhare it shouldnt have.
i am going to check it out, let u know, thanks
chris
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Chris, Art is giving you great tips, but I'm still trying too.
See my post above for EZK location. It's the one you thought was the FI ecu.
Bruce
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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i know what one is the FI ecu, cause i had to replace it after it got water in it, its behind the passenger kick panel. the car also ran with that computer compleatly removed cause when the FI ecu got water in it it shorted out and told the injectos full spray and flooded the motor. so in a atempt to get home i unpluged the ecu abd cranked over the car to try to unflood it, well to my surprise it started and ran for 10 sec on all the excess fuel then died. the way i got the car home (less than a mile) walked home got about 6 feet of fuel line and a helper friend and a can of starting fluid. now i know this is dangerous, but here goes. i put the fuel line on a vacuume port centraly located on the intake, routed inside car, told my buddy to spray away into the hose in small spurts. the whole time the FI ecu was never pluged in. well it ran good and made it home.
well i took down all the trip panels under the dash and found said ignition ecu. its under the drivers side above the brake pedal
its bosch purple tag
and it says: 0 227 400 109
made in germany (yea leave it to a german part to go bad, love german cars but japs got them beat for fual and spark systems)
anyway it smelled weird almost burned smell, took it apart but everything looks good, gona go look at it with good light and see if its a broken solder joint.
thanks again
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Posted by bigfoot on Sun Sep 18 09:18 EST 2005:
"its a b280. the number 15 (Coil) terminal has 2 wires 1 that i traced back to the power stage and the other goes all the way to the FI ecu..."
If you traced a blue wire from the coil to some ECU, it had to be the Ignition (EZK) ecu -- NOT the FI. There are no Coil wires going to the FI ecu. None. So when you said you were going to look for the EZK ecu, I replied you had already found it.
Anyway, from your symptoms it's not likely an EZK ECU problem unless it's the Power Stage control wire (green) from terminal 16 going to power stage terminal 1. But I have never heard of that (or the ecu) as causing your problem.
IMO, the most likely problem is the PS connector contacts or the PS itself. They are known to fail, especially with age and due to the heat sink conditions I mentioned before. A bad ground on the intake (2 brown wires) might do it too.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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does anybody have a wiring diagram that tells what wires go where from the EZK computer?
i want to start checking with the ohm meter to make sure the wires not broken.
thanks chris
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oh yea forgot to tell ya its the prv v6 2.8 in the car, i like the engine but there does not seem to be much in the FAQ section on them
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